SR 512 begins at a partial cloverleaf interchange with I-5 in Lakewood, a suburb of Tacoma in the Seattle metropolitan area. The interchange only uses three cloverleaf ramps, with turns from southbound I-5 to eastbound SR 512 accessed via a traffic signal; beyond the interchange, the highway continues west to an intersection with South Tacoma Way. The six-lane freeway travels southeast along the north side of Joint Base Lewis–McChord and through an interchange with Steele Street before entering the suburban community of Parkland. SR 512 then intersects Pacific Avenue, carrying a section of SR 7, in a partial cloverleaf interchange located near the Pacific Lutheran University campus. The freeway continues east with four lanes through Midland, passing under overpasses for school buses and the Tacoma Rail system, before reaching an interchange with Portland Avenue near Franklin Pierce High School. SR 512 then crosses over Swan Creek and enters the exurban area of Summit, passing residential subdivisions and farms surrounding an interchange with Canyon Road, which leads to the Fredericksonindustrial area. The freeway travels into Puyallup and intersects 94th Avenue East on the west side of the South Hill Mall. It then turns north and reaches a partial cloverleaf interchange with SR 161 at 31st Avenue Southwest, marking the beginning of a concurrency between the two state routes. SR 512 and SR 161 continue north through the residential neighborhoods of Puyallup before reaching the Washington State Fairgrounds and turning east to intersect Meridian Street. The freeway travels east around downtown Puyallup and intersects Pioneer Avenue before crossing over the BNSF Railway's Seattle Subdivision tracks and the Puyallup River. SR 512 terminates shortly after crossing the river at a trumpet interchange with SR 167. SR 161 travels west with SR 167 to an intersection with Meridian Avenue, which it follows to Federal Way; SR 167 continues east to Sumner before turning north onto the Valley Freeway. SR 512 is maintained by the Washington State Department of Transportation, which conducts an annual survey on state highways to measure traffic volume in terms of average annual daily traffic. Average traffic volumes on the highway in 2016 ranged from a minimum of 44,000 vehicles at its eastern terminus with SR 167 to a maximum of 110,000 near its western terminus at I-5. The entire route of SR 512 is designated as part of the National Highway System, a national network of roads identified as important to the national economy, defense, and mobility, and is listed as a Highway of Statewide Significance by the state legislature.
History
The first road to connect Fort Steilacoom and southern Tacoma to the Puyallup Valley was Byrd's Mill Road, established in 1852 and designated by the Oregon territorial government as an official government road. It was later upgraded into a military road and designated as a state historical road in 1941 by the Washington state government. At the turn of the 20th century, Lakeview was connected to Parkland and Puyallup by a series of country roads that were straightened in the early 1910s to form 112th Street South. These roads became Secondary State Highway 5G, which ran from in Puyallup south to and west past the Tacoma-Mount Rainier branch of PSH 5 to south of Tacoma. Washington renumbered its highways in 1964 and SSH 5G was assigned to become SR 512 when the new system took effect in 1970. In 1970, the new system of state routes took effect and SR 512 was officially established; at the time, it was a freeway west of Vickery Avenue, continuing to Puyallup on 112th Street. By 1972, the highway was expanded and reconstructed to become a divided freeway. The original path is approximately SR 512 from South Tacoma Way to Steele Street, Steele Street to 112th Street, then 112th Street into Puyallup, where it turns into 39th Ave to Meridian, where the original route is lost to improvements, but the route would continue on to Shaw Road. The interchange with Pacific Avenue was rebuilt in the late 1980s. In 2002, the interchange with Interstate 5 was modified from a full cloverleaf to a partial cloverleaf. The Southbound I-5 cloverleaf to SR 512 eastbound was removed. The Southbound to Westbound ramp was modified to accommodate for left turns onto eastbound 512 by adding a traffic signal. There were other planned improvements, but due to tax revenue shortfalls, the rest was shelved. In the future, WSDOT plans to again reconstruct this interchange and at least Steele Street interchange as part of the Interstate 5 HOV project. Due to congestion near the South Hill Mall in Puyallup, WSDOT is studying improvements to two interchanges on SR 512, including auxiliary lanes, loop ramps, and flyover ramps.
